How can i update a document with a rich text field data which contains text and images?

I have been using Nintex Document generation and it has been working successfully. The only issue I have is when trying to update a document with rich text field data which contains text and images, I have been unsuccessful in doing so. It does not seem possible for some reason, not sure if anyone else has experienced this. Please can the community assist me with a solution for this issue or a possible workaround.